LOS ANGELES – Unlike the regular flu, young people will be the priority for vaccinations against the swine flu when the vaccine becomes available by late October, county health authorities said Wednesday.

In the months since the HINI virus that causes swine flu first surfaced in Los Angeles County, 157 people have been hospitalized with the illness. Twenty-five people have have died from illness, Jonathan Fielding, head of Department of Public Health, said at a news conference in Los Angeles.

Most of those who died from swine flu had other medical complications, or were pregnant, said Fielding.

The virus has mostly affected people under the age of 24, Fielding said, and that age group will be targeted to receive the initial vaccinations. Pregnant women have also been particularly susceptible, he said.

Normal strains of flu tend to be much more dangerous for older people, with 90 percent of fatalities occurring among people 70 years or older.

Initially, the county will experience shortages of the vaccine as it begins to receive the shots, Fielding said. He said the department may regulate who can receive the initial shots, since older people appear to have some immunity towards the virus.

That could lead to a challenge for officials in making people understand the difference between the swine flu and the regular seasonal flu.

Unlike the regular seasonal flu, which strikes mostly in the winter, swine flu cases have continued to surface since the illness was first reported in the county in April, he said.

“This flu season has not been like the usual,” he said.

Fielding also said the department anticipates the infection rate for swine flu to climb once children go back to school.

Swine flu, like the normal flu, is best avoided by frequent hand-washing or using hand sanitizer, he added. People who get sick don’t necessarily need to go to the hospital, unless their symptoms get severe, said Fielding.

The vaccine will require two shots over a three-week period. Doctors and health agencies are being encouraged to contact the health department to sign up as distributors of the vaccine.

Dr. Takashi Wada, of the Pasadena Public Health Department, said he expects to be a part of the distribution network. He said that the department would use private physicians to distribute the vaccine.

“If we relied just on our facilities, we could be overwhelmed,” said Wada.